that something is to cold .
what happened was: 1. the sea water around the poles used to be heated by the sun but the pole ice never melted. 2. This changed and instead the ice was being heated but the sea water was freezing...
Crushed ice would melt faster because it has more surface area, and it probably has a less density than regular uncrushed ice.
With big refrigeration units.
It is a mixture of the two.